Process of making magneto-generators



Aug. 12 1924.

, P. J. GILINSON PROCESS OF MAKING MAGNETO GENERATCSRS Filed Jan,

Ir Z Z I veniar;

g y 1 g g Patented Aug. 12, 1924.

UNITED STATES 1,504,619 PATENT OFFICE.

rmmr J. cmmson, or mwnnnnnssncmrsnr'rs, nssmnoa r nnmzn nnncrnrc cone, or LOWELL, mssncnusn'r'rs, A. conronn'rron or mun.

PROCESS OF MAKING IAGNETO-GENERATOB S.

Application fled January 13, 1822. Serial Kc. 529,048.

To all iohom it may concern:

Be it known that I, PHILIP J, GILINSON, a citizen of the United States of America. and resident of Lowell, in the county of Middlcsex and State of Massachusetts, have invented new and useful Improvements in Processes of Making Magneto-Generators, of which the following is a specification.

This invention concerns electrical apparatus, such for example as magneto-generators and relates more particularly to a process useful in the production of such apparatus.

As usually constructed the field magnets of magneto-generators are provided with iron pole pieces between which rotates the armature or rotor. Such pole pieces, whether of laminated or solid construction, are commonly fixed in position relative] to each other and to the axis of the rotor y casting the metal of the generator casing around them. This may be done either by the die casting process or by sand casting. The die casting process is, however, initially expensive by reason of the cost of the necessary dies, and in the subsequent practice of this process, such accurate machining of the exterior surface of the pole pieces is necessary to enable their insertion 1n the dies, as to maintain a high cost of production. In the sand casting method, the roughly cast pole pieces are placed in the mould wherein the generator casing is to be formed and ositioned as accurately as le relative y to one another and to t e core. When the metal of the is poured into the mould the pole pieces are firmly embedded therein butit is found in practice that it is almost impossible to maintain the pole pieces in proper relative position during the pouring and cooling of the casing metal, so that 1 when the pole pieces are machined to final shape, a wide air gap is formed between the pole pieces and rotor with consequent loss of efiiciency in the generator.

The object of the present invention is to provide for securing the pole pieces within the generator casing in such a manner as shall ensure accuracy of position of such pole pieces, both with respect to each other and to the rotor axis, while at the same time facilitating and machining of such pole pieces and decreasing the cost of production.

To this end the invention may consist in providing a unitary structure comprising the two pole pieces together with spacer members integrally joined thereto. This structure is preferably formed as a cored casting, the heavy pole pieces bein united by relatively thin connecting or bri ge portions. After roughly boring out the cored opening in the member, the holes in the pole pieces necessary for securing the U-shaped magnets are drilled, and the connecting metal between the adjacent ed of the pole pieces is sawed almost throng on lines defining the edges of the pole pieces. The pole casting is then placed in the mould for the generator casing, the core passing through the roughly bored opening inthe casting and serving to center the latter. After the casing metal has been poured, the casing is removed from the mould and the cored opening therein is bored to reduce the pole faces to finished size. This'borin operation serves to break through the meta at the bottom of the saw kerfs, permitting the connecting bridge pieces to drop out, thus leaving the finished pole pieces accurately in alignment.

As illustrative of this method, reference may be had to the accompanying drawings, in Which,- i

Fig. 1 is an end elevation of the pole piece structure before machining;

Fig. 2 is a top plan view of the same;

Fig. 3 is'a transverse cross section of the pple piece structure after machining and fore incorporation of the same in the generator casing;

Fig. 4 is atransverse cross section illustrating the device of Fig. 3 as embedded in the casting forming the casing of the generator;

Fig. 5 is a cross section similar to Fig. 4, but showing the pole pieces as separated and the U-magnets in position; and

Fig. 6 1s a fragmentary, side elevation of the generator casing to smaller scale, showing the position of the pole pieces therein.

Referring to Figs. 1 and 2, there is shown a unitary structure illustrated as a casting and comprising the relatively hea pole ieces 1, 2, connected by the relativeiy; thin Bridge pieces 3, 4, such pole and ridge hereinafter described. The pole piece structure is formed of magnetic material, such downwardly from the outer faces of the pole pieces 1, 2,, respectivel These drill holes are for the reception 0 the U magnets hereinafter referred to," it being understood'that one or more of such magnets may be employed and that corres onding numbers of the openings 8, 9, will e formed in the respeotive pole pieces. -After the drilling of t e o en1ngs'8, 9, a plurality of longitudinal s ots such as 10, 11, are formed at the sides of the bridge pieces 3, 4, respectively,

such slots serving to define the adjacent edges of the pole pieces. These slots may consist of saw kerfs extending inwardly toward the bore 7, and arran ed symmetrically with respect to .the axis of the -.bore. These saw kerfs are'of a depth such as to leave just su'fiicient metal connecting the pole and bridge pieces to maintain the integrity of the structure during the succeeding operations. After such machinin of g the pole structure has been completed, it is- I placed in a two-part mould arranged for the castlng of the generator casing. The

pole structure ma be supported in the mould by means 0 a core passing through the bore 7 whereby it may be accuratel retained in position. The mould is then lled with molten metal of a non-magnetic character, such forexample as aluminum, whereby to form the generator casin 12, the metal of the casing flowing aroun the fins 5, 6 of the pole structureand securely holding it in position. After the cooling of the cas1ng,.it is withdrawn from the mould w1th the ole structure securely embedded therein. nthis connection it may be notedthat eventhough the pole structure as a whole should move slightly during the castin 0 ration, the'relative positions of the o e aces 1', 2 would not be affected therey.- The bore 7 is now subjected to a boxinlg operation whereby its diameter is somerated t increased and whereby thepole faces are finished as indicated at 1", 2, respectivel (F1 5). In thus reboring the open: mg su cl'ent metal is removed to break throu h the bottoms of the slots .10, 11, where the bridge pieces-3, 4 are se a:

rom the pole pieces,- such bri p eces dropping outand leaving, the o 0 pieces as m ependent members unoonneted by magnetic material. The removal of the bridge pieces 3, 4 results in the formation of arcuate recesses 13 and 14 between the pole pieces, such recesses roviding the desired clearance between the casing 12 and the rotating parts of the armature. The U- magnets may now be inserted in the 0 enings 8, 9, and the device is ready for su sequent operations not related to the present invention.

In accordance with the method above described, it is evident that the pole pieces are maintained in relatively fixed position with respect to each other durin the preliminar steps of the operation, inc uding the rougi boring of the same and the embedding of such pole pieces in the casting of the casing. The integral connection between the pole pieces is of very considerable advantage in boring the same to form the pole faces thereof as it provides continuous metal for engagement by the cutting tool, thus avoiding any'tendency to form an elliptical bore, such as is frequently occasioned 1n attempting to bore out pole ieces which are entirely separate from eac other. Moreover, the integral connection of such pole pieces serves to prevent separation of the same or relative twisting or rotation of the parts during the casting of the casin so that but little machining is necessary t iereafter to finish the pole pieces, with the result that the air gap may be made of minimum width and withl resultant efficiency of operation.

While it is preferred to secure the pole structure in the casing by casting it therein, it is contemplated that it might otherwise be secured in such casing without materially affecting the carryin into effect of the moreessential steps of t e process and it is further contemplated that roughly machined pole piece structures such as illustrated in Fig. 3 might well be manufactured and sold for use in constructing generators or otherelectrical apparatus regardless of the particular mode of securing such ole structures in the casings with which t ey might thereafter be amociated. While as herein shown a pair of pole pieces are employed, it is also contemplated that a greater number might be used, the mode of com structing and securing the same in the generato'rcasing being in all respects similar to that above described with respect to the biolar structure herein disclosed.

aving thus described the invention, what I desire to secure by Letters Patent of the United States is:

lz'That process of making electric generators which comprises forming a pair of inte llyunited pole pieces, simultaneously mac ining the pole faces bf'said pole pieces, and separating such 'pole'pieces during the machining thereof 2. That process of making magnetos which comprises casting a pair of integrally united pole pieces, machining the pole pieces, and thereafter separating said pole pieces.

3. That process useful in making. electrical machines which comprises forming a pair of pole pieces integrally united by connectin elements, partially severing such pole pieces from said connecting elements on lines defining the. adjacent edges of said pole pieces, and thereafter machining said pole pieces whereby to finish the pole faces thereof and simultaneously to separate the connecting elements from such pole faces along the lines of the previous partial severing. j

4. That process of making pole pieces for electro-magnetic machines which comprises casting said pole pieces with integral connecting elements, partially separating said pole ieces and connecting elements by inward y directed incisions, machining the pole pieces, and completing such separation y removing metal rom the pole faces of said Elle pieces.

5. at process of making pole pieces for magnetos which comprises forming an integral, cored casting having the respective po e pieces united by relatively thin connectmg metal, boring said casting whereby almost to sever the pole pieces from the connecting metal on lines symmetrical with the axis of the bore, and again boring such casting to form finished faces upon the pole pieces and simultaneously to complete the severing of the same from the connecting metal.

6. That process of forming independent pole pieces for magnetos which comprises forming an integral structure having pole pieces united by connecting elements, the

- lines of junction of said pole pieces and connecting elements-being relatively weak, simultaneously machining said pole pieces, and separating such pieces and connecting elements along the relatively weak lines of junction therebetween.

7. That process of making magnetos which comprises forming a structure consisti of a plurality of pole pieces with integra connecting elements, arranging said structure within a suitable mould, pouring fusible material into such mould to form the magneto. casing, and thereafter removing the connecting elements from between said pole v 8. at mode of forming magneto machines which comprises forming a metallic structure of magnetic material having rela tively light and heavy arts, securing said structure at its heavy portions to the magneto casing, machining the heavy parts of said structure to provide finished surfaces and to separate the light ortions of said structure from the heavy portions thereof,

and removing such light portions from the casing.

9. That mode of constructing magneto machines which comprises forming a casting consisting of relatively heavy pole pieces integrally united by lighter connecting members, weakening such connecting members along their lines of junction with the pole pieces, embedding the casting in the substance of the magneto casing, and breaking out the connecting members of said casting along the lines of weakening thereof.

10. That method of making magneto generators which comprises forming a c'ored casting having a pair of pole pieces connected by relatively thin elements, roughly boring the cored o ening-in said casting,

partially severing t e pole pieces from the connecting elements by longitudinal, external saw kerfs symmetrically spaced relatively to the axis of the bore, embedding such casting in the generator casing, and boring the opening in said casting to a diameter sufficient to break through the metal at the bottom of the several saw kerfs, whereby to separate the connecting elements from the pole pieces.

11. That process of making magnetos which comprises forming an integral structure having pole pieces spaced about a longitudinal bore, utilizing such bore for centering said structure in a mould, and filling said mould with molten material whereby to form a magneto casing having said structure embedded therein.

12. That method of making magneto generators which comprises casting an integral structure of magnetic material consisting of a plurality of'spacedpole pieces and integral connecting members bridg ng the spaces between said pole pieces, said parts defining alongitudinal, cored opening boring said opening roughly to the desire diameter, partially separating said bridge members from the pole pieces by longitudinal saw kerfs extending inwardly toward the bore, said saw kerfs' being symmetrical with respect to the axis of the bore and defining the adjacent edges of the pole pieces, 1nserting said casting in a mould, centering said casting therein by means engaging its bore, filling such mould with molten metal to form the generator casing,. casing from the mould, and reboring the opening in said first named casting to final diameter, thereby breaking out the bridge members between the saw kerfs.

13. A device for use in the construction of magneto generators comprising a plurality of pole pieces and bridge members integrally uniting said pole pieces, the pole pieces and bridge members defining a longitudinal, circular bore. said bridge members being structurally weak along their lines of removing the 14. A structure for magneto generators having fixed therein a pole piece structure comprising a plurality of iron Bole pieces integrally united by bridge rnem ers of the same material. said ole pieces and bridge members defining a circular bore of a diameter less than is required for the reception of the generator shaft and rotor, said pole piece structure having longitudinal channels extending inwardly toward the bore along lines defining the junctions of the bridge members and the respective pole pieces.

Signed by me at Lowell, Massachusetts, this third day of January, 1922.

PHILIP J. GILINSON. 

